Analysis of an Optofluidic Biochemical Sensor

In this presentation we introduce a novel optofuidic biochemical sensor in which detection is based on the contrast between the refractive index of a target biomaterial and the ambient carrier fluid. The sensor consists of parallel micochannels embedded in a substrate with an orientation perpendicular to its surface. The central microchannel is illuminated by a focused beam of light and the periodic spacing of the channels combined with the contrast in refractive index between the fluid and the substrate act to confine and guide the incident light. The transmission spectrum through the substrate depends on the dimensions, periodicity and refractive index of both the carrier fluid and the substrate material. Sensing is achieved via accumulation of a thin layer of target biomaterial on the surface of the microchannel walls, which are functionalized to bind with the material as it flows through the system. The presence of the layer causes a shift in the optical transmission spectrum. We use full-wave electromagnetic analysis to study the transmission spectrum of the sensor at optical wavelengths as a function of various device parameters and material properties. Our analysis indicates that the sensor holds potential for compact and low-cost biosensing applications.